Hello, in this OpenTK application why can you get the perfect scale with Math.PI?

time = (time >= Math.PI) ? 0.0 : time + e.Time; variableScale = (float)(Math.Sin(time));

I know that Sin works best for 0..360 circle degrees range, but Math.PI related to time is strange.

If you have any references about and links to share please post here. Thanks.